Marc Andreessen

Marc Andreessen's name is supersized in the small circles of Silicon Valley, as an entrepreneur, advisor, investor and now as a power tweeter. The Netscape Communications cofounder turned to investing full time alongside partner Ben Horowitz in 2009. Andreessen was a seed investor in Twitter and LinkedIn and a later-stage investor in Skype (acquired by Microsoft in 2011), Groupon (IPO 2011) and Zynga (IPO 2011). He now sits on the board at eBay, Hewlett-Packard, Facebook, Anki and Oculus VR, the maker of the groundbreaking virtual reality headset Oculus Rift. Andreessen's also guided his firm's investments in Fusion-IO (IPO 2011), Airbnb, Glam Media and Instagram. In 2014, he's somehow found the time to become something of a Twitter chat leader, engaging with his 80,000+ followers through multi-tweet arguments about topics from the future of media to the ethics of anonymous sharing apps.